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Full text of "The Cambridge Natural History"

DEVELOPMENT   OF    HAIR

elongated and converging slightly above amI Inflow. Dr. Maurer
has called attention to the remarkable likeness between the
embryonic hair when at this stage and the simple tttnise.-or^ans
of lower Vertebrates. Later there is formed below this a
denser aggregation of the eorium, vrhieh ultimately beeomc.s

the papilla of the hair.
This IK the- apparent
homolojjjuc, of tliu* first
formed part of a
feather, \vhieh projects
as a papilla before the
epid*>rralH hu« under-
gone any modiltication.
Il«*ut'*! thert» is from
the, very tirst a din*»r-
etu*e between fratlierH
and h;urs-—-'UdiHeivixtt*.
whh*h mu^t be o.'uv-
borno in mind,
illy wlien we
consider tho Mr«»nj^
K u pe. r ii tt I ul rime m-
blan«*e l»etween h;ur«
and tho ftiisiplo bnrb-
<. Still

full

Fr<*, 2.-— Four «Htt$pra'ms of utaircs* in ttu'r <tavwloj»m«*«t

mnrnnui!*   *           At       t        t       #

; 1<* C% 1>,   later till* Kttm*   f>t

A* K«ttli^«t »tage in one of
in whUth th« dtiniial itftpiila ftppenrn
tbrv««taffM in the jl«wlopmi«t «f tho hair in th«

ii tun tin wtsoryo.    «<7,   ilnir-i>ulb ; rr«, hortxy layn't

of the  epIdwiniH ; fttlt   hair * follicle 5   j/rrw,  hulr-   dl*|»rt*HB€*<l   into U tltl»U-

;   A,   h»frf   in

or*    tint   «ur-

!„„ Kft*t«'t tin*
-1       KM Ut Mire,

ift
IB

„     Kt*t«'  tn*
face;   m«<j»  Malpighiaik   layer  of i'i»i<!«rutlN ;  i*pt    -1,      KM Ut Mire, 'VMJ
dermal papilla; «?6» d«v«l<ij>l»g *Mj1*acemt» glamin ;   lined    with    <**»lirt
"                              fri,iu    tho
alptghti, but
is filled with a continuation of the more*  «up«%rticial t**4lH of the
epidermis,     This is the hair-follicio, arid from the <*p«l«trini« eells
arises the hair by direct incstaii«irj>hoH!« of thong eells ; there m
no excretion of the hair by tin© cells, hut the celts fajcome tlw*
hair. From the lu&ir-folliele also grows out a |»*iir of
glands, which eerve to keep the fuHy~form&d hair moidt.
J)r. Meijerle1 has liitely descsribed in uoino detail tho
xxl.